trouble with rear sprocket/chain

I've spent the better part of a day aligning the chain with the front and rear sprockets and making sure the chain isn't rubbing on the frame or tire. But, the chain doesn't seem to want to mesh smoothly with the rear sprocket. It keeps binding up and coming off the sprocket. It makes a lot of noise even when it does manage to stay on for a while. Any hints as to how to smooth it out?

Here's one thing I noticed today. If your rear chainstay is angled outwards as it goes back towards the wheel, you may have issues. The tensioner will be at the same angle of the chainstay, and this makes the chain run at an angle across the tensioner wheel. If you adjust it so it's quiet, it takes the chain off the sprocket.

One solution would be to "twist" the bracket. I tried to do it with a couple pair of pliers today but failed. Need to figure out a good way to do it.

To bend the tensioner bracket it really helps to have a table mounted vise and a large pipe wrench and/or a small sledge hammer....Pliers may work but you'd probably have to look like Rambo to do it using that ;-)

Hope this helps you....Good luck!

Andrew

PS - 2 pipe wrenches may work tho....just need the longer ones for more leverage....

Here's one thing I noticed today. If your rear chainstay is angled outwards as it goes back towards the wheel, you may have issues. The tensioner will be at the same angle of the chainstay, and this makes the chain run at an angle across the tensioner wheel. If you adjust it so it's quiet, it takes the chain off the sprocket.

One solution would be to "twist" the bracket. I tried to do it with a couple pair of pliers today but failed. Need to figure out a good way to do it.

Here's one thing I noticed today. If your rear chainstay is angled outwards as it goes back towards the wheel, you may have issues. The tensioner will be at the same angle of the chainstay, and this makes the chain run at an angle across the tensioner wheel. If you adjust it so it's quiet, it takes the chain off the sprocket.

One solution would be to "twist" the bracket. I tried to do it with a couple pair of pliers today but failed. Need to figure out a good way to do it.

Click to expand...

What is "rear chainstay"? Is this different from the tensioner? Am I missing something?

The rear chain stay is the piece of the frame that you typically mount the chain tensioner on....It is the tube that runs parallel to the ground from the bottom bracket to where the rear wheel attaches to the frame.

The rear chain stay is the piece of the frame that you typically mount the chain tensioner on....It is the tube that runs parallel to the ground from the bottom bracket to where the rear wheel attaches to the frame.

Hope this helps

Andrew

Click to expand...

Thanks. Being an old motorcycle mechanic, I would think of that piece as the swingarm, although the term doesn't really apply to a bicycle.

I've spent the better part of a day aligning the chain with the front and rear sprockets and making sure the chain isn't rubbing on the frame or tire. But, the chain doesn't seem to want to mesh smoothly with the rear sprocket. It keeps binding up and coming off the sprocket. It makes a lot of noise even when it does manage to stay on for a while. Any hints as to how to smooth it out?

Click to expand...

You should mount the rear sprocket the way the factory designed it! (don't try to change things around.)
The tire will be fine if the chain rubs it a little... if it really bothers you, you can put on a smaller tire.
& last... bend the chain tensioner however it takes to where it feeds the chain nice & straight onto the rear sprocket!

You should mount the rear sprocket the way the factory designed it! (don't try to change things around.)
The tire will be fine if the chain rubs it a little... if it really bothers you, you can put on a smaller tire.
& last... bend the chain tensioner however it takes to where it feeds the chain nice & straight onto the rear sprocket!

Click to expand...

I have mounted the sprocket according to directions. At first, I thought the problem was that the chain was rubbing against something, but then I realized that it's the chain not meeting with the sprocket the way it should that is the problem. I'm going to file the sprocket teeth and see if that helps.

I have mounted the sprocket according to directions. At first, I thought the problem was that the chain was rubbing against something, but then I realized that it's the chain not meeting with the sprocket the way it should that is the problem. I'm going to file the sprocket teeth and see if that helps.

Click to expand...

The last sentence of that post is the most important for your chain problem...
Make sure the tentioner is feeding the chain onto the sprocket PERFECTLY. (bend it if you have to!)

I've filed the sprocket teeth and it definitely is better although still noisy. I'm hoping that will quiet down as the bike is broken in.

Click to expand...

Nope. Still no good. I can see what's going on here. No matter how I align everything, the idler wheel keeps pushing the chain off the sprocket. This is my second build and I had no of this problem before. I'm thinking I'm going to try to bend open the rear fork a bit, so I'll have more room to work back there, but I don't know if that will help. Four times now, I've had to drag the bike back to the shop with a seized rear wheel.

Looks like I won't have to bend the frame at all. The problem was that the bolts holding the tensioner to the frame were stripped so I couldn't keep them tight. Every time they'd loosen up, the tensioner moved and caused the chain to leave the sprocket.